The present invention relates to a molded article including an internal member wherein the internal member is encapsulated within the molded article, as for example, a fiber optic cable encapsulated within a plastic article.
Insert molding is well known and is typically used for producing articles having components encapsulated within the plastic article. The inserts are typically rigid components made from metals or plastic and are sufficiently rigid enough themselves to withstand the forces and temperature of the incoming injected plastic during their encapsulation.
U.S. Pat. No. 3,476,852 shows a composite plastic container molded by first inserting into the mold cavity preformed plastic inserts, which are then surrounded by an injection of similar plastic to bond to the inserts by melting the edges of the inserts and forming a welded bond. The preformed inserts are relatively large compared to the injected plastic volume and are well supported within the closed mold cavity. A second example of injected resin welding to plastic inserts is shown in U.S. Pat. No. 4,410,480. Here two components are welded into a composite body by the injection of the resin. Again they are large compared to the volume of injected resin and well located and supported within the closed mold cavity.
U.S. Pat. Nos. 4,314,960 and 4,599,062 show molds into which are loaded metal electrical cables or connectors for encapsulation by plastic which is injected into the mold. Here the inserts are sufficiently rigid and made of a material resistant to the thermal and pressure shock of the injected plastic, to remain well located. U.S. Pat. No. 3,003,189 shows a wire feeding mechanism for insert molding articles containing embedded wire. In this machine, the metal is held in a straight orientation and plastic is molded around it. Accurate positioning of the wire is not an issue. Similarly the wire is not adversely affected by the heat of the injected plastic.
U.S. Pat. Nos. 4,470,784 and 4,959,000 show insert molding methods whereby the insert is positioned within the mold cavity by retractable means so that it can be completely surrounded by the injected plastic. The '784 patent uses retractable pins that withdraw into the insert itself and the '000 patent uses retractable pins that withdraw into the mold cavity wall. In both cases the injected plastic does not adversely affect the insert by virtue of injection pressure or temperature.
U.S. Pat. No. 4,448,741 shows a slender insert being partially encapsulated in resin by a two stage molding process including the step of molding spacers onto the insert in the first molding stage, followed by a second molding step. Thus, the insert is exposed to two injection molding operations and is therefore more likely to become damaged from this additional handling and processing.
It is a principal object of the present invention to provide a molded article including an internal member encapsulated therein.
A further object of the present invention is to provide an article as aforesaid which is easy to prepare and which can be prepared by injection molding techniques without damage to the internal member and which exposes the internal member to only a single injection molding operation.
A further objective of the present invention is to provide an article as aforesaid wherein the internal member may be a fiber optic cable which is accurately located within the article.
Further objects and advantages of the present invention will appear hereinbelow.